Fixture Unit Counts for Uniform Plumbing Code (UPC) 1

[rywill01]

I am attempting to use fixture counts to determine the demand in my water model. However, for the flushometer valves (water closets)there are two tables in the Code, one is in Chapter 6 table 6-5, and another one in Appendix A table A-2. The two give very different values for the same fixture being flushometer valves. I need help in trying to determine which table I should use?

I read through the code, but can't find any clear description about why I would use one table over another. Thank you, for any assistance!

 

[PEDARRIN2]

You need to be very careful when trying to equate plumbing fixture units to civil gpm in a model. Fixture units are statistically derived values which relate probability of use to flow. 100 fixture units in an office building will give you a much different flow than 100 fixture units for a sports stadium.

Example is 10 water closets is roughly 100 fixture units. Using Hunter's curve (statistical evaluation of flow), which the UPC is based upon, you would expect the peak flow to be around 67.5 gpm, which is a bit more than 2 water closets flushing at the same time. In the stadium, you could have all 10 water closets flushing simultaneously, which could require a peak flow of 250 gpm.

If you are going to use them, use the table in Chapter 6 since it is in the requirements and the appendix is not.

 

[rywill01]

Thank you, for your response!